1. Field of the Invention
The present invention relates to a solid electrolyte type fuel cell.
2. Description of the Prior Arts
As a flat-plate type solid electrolyte fuel cell, a flat-plate type solid electrolyte fuel cell as shown in FIG. 12 is pointed out.
Cell member 54 comprises solid elecrolyte layer 51, air electrode layer 52 formed on one side of said solid electrolyte layer 51 and fuel electrode layer 53 formed on the other side of said solid electrolyte layer 51. Distributers 55 are arranged on both electrode surfaces of said cell member 54. Said distributer 55 is made of metallic felt, metallic foaming body, ceramic felt, ceramic foaming body or the like, each of which has gas permeability, electrical conductivity, atmosphere resistance and cushioning property. Separators 56 are arranged on the outer sides of the distributers 55 so that separators 56 can press the distributers 55 to the electrode surfaces of the cell member 54. Separators 56 are electrically connected to one another, thereby an electrical circuit being formed. A space formed by the air electrode 52 and the separator 56 serves as an air path and a space formed by the fuel electrode 53 and the separator 56 as a fuel path. When the cell member 54 is practically used as a fuel cell, a fuel cell is constituted by stacking up the cell members 54 in a plurality of layers.
As another flat-plate type solid electrolyte fuel cell, a flat-plate type solid electrolyte fuel cell shown in FIG. 13 which Professor Steele introduced in his literature (CERAMIC ELECTROCHEMICAL REACTORS, 1987. B. C. H. Steele) is pointed out.
Cell member 69 comprises flat-plate solid electrolyte 66, flat-plate air electrode 67 formed on an upper surface of the solid electrolyte 66 and flat-plate fuel electrolyte 68 formed on a lower surface of the solid electrolyte 66. Fuel electrode 64 having fuel path 63 is formed on an upper surface of separator 65. Air electrode 62 having air path 61 is formed on a lower surface of the separator 65. The cell member 69 is put between two separators 65, each of which has the fuel electrode 64 and the air electrode 62. Air is supplied to the air path 61 enclosed with the air electrode 62 on the side of the separator and the air electrode 67 on the side of the cell member. Fuel is supplied to the fuel path 63 enclosed with the fuel electrode 64 on the side of the separator and the fuel electrode 68 on the side of the cell member. The separators 65 are electrically connected, via resistance 70 thereby an electrical circuit being formed. When a fuel cell is practically used, high voltage can be obtained by increasing the number of the cell members 69 and alternately putting the cell members 69 and the separators 65 one on another.
Further, monolithic type fuel cell shown in FIG. 14 which Professor Steele introduced is pointed out. Cell member 74 is constituted by arranging flat-plate fuel electrode 72, whose internal surface is constituted in the form of honey comb, on one surface of flat-plate solid electrolyte 71 and air electrode 73, whose internal surface is constituted in the form of honey comb, on the other surface of the flat-plate solid electrolyte 71. The fuel electrode 72 in the form of honey comb is mounted on the surface of the flat-plate solid electrolyte at right angles to the air electrode 73 in the form of honey comb. The cell members 74 are stacked up in layers by means of the separators 75. As shown in FIG. 15, fuel is supplied from fuel supply manifold 77 to honey comb space 76 of the fuel electrode 72 and excessive fuel is discharged from fuel discharge manifold 78. Air is supplied from air supply manifold 80 to honey comb space 79 of the air electrode 73 and excessive air is exhausted from air exhaust manifold 81.
There, however, have been the following problems in the above-mentioned flat-plate type solid electrolyte fuel cell:
(1) A type shown in FIG. 12:
1 In this fuel cell, manifolds for supplying fuel and air to the fuel cell are formed. O rings 57 are used for a gas seal of the manifolds. When O rings are strongly pressed to prevent gas from leaking, a cell portion of a thin film layer is liable to be broken. PA1 2 Even if cushioning material such as Ni felt is introduced, the cell portion of a thin film layer has to carry a load invariably. PA1 3 When the cell becomes larger, it is easy to break. PA1 1 This type has no cushioning property. Therefore, when the cell is compressed, it is easy to break. PA1 2 A structure of a tie-in portion of an external manifold becomes complicated. PA1 3 In the case of monolithic cell type, the external manifold is hard to mount on a honey comb portion and there is a problem in the gas seal.
(2) A type of the fuel cell which Professor Steele proposed: